docs: def main():
      """
      Executes the given command. Returns error_message if command is not valid.
  
      Returns:
          Output of the given command or error message if command is not valid.
      """
      try:
          command = sys.argv[1]
      except IndexError:
          return error_message()
  
      try:
          module = importlib.import_module('i18n.%s' % command)
          module.main.args = sys.argv[2:]
      except (ImportError, AttributeError):
          return error_message()
  
      return module.main()